Questions tagged [storage]

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Primary File Organization in DBMS - Files of ordered records (sorted files)

"Fundamental of Database Systems", 3rd ed. by Elmasri and Navathe, page 136 says: "We can physically order the records of a file on disk based on the values of one of their fields [...]&...
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Is reading contiguous pages (let's say 4KB) any faster than reading non-contiguous pages on SSDs?

I'm working my way on a problem which requires me to store elements in fixed 4KB-sized pages on an SSD. Each page is requested once for some computation on its elements, and then the CPU requests for ...
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1 vote
2 answers
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How can I write 2^65 on my 64-bit computer?

This is possibly a very trivial question for this site. If I have a 64-bit laptop that means 2^64 combinations in total are possible. But I can even get $2^{(x>>>64)}$ on my laptop. Now, it ...
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How to calculate number of tuples in a page?

I have been working on this particular question since yesterday and I can seem to figure out how to solve it: Assume that your files are organised based on slotted page array which contains a header (...
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Using B+Tree to implement index, when the index-key size and the data-block size are of the same order

I want to implement an Index using a B+Tree as the underlying data structure. The index will have to support key sizes which are of order of my block size, what means I cannot save all the key as a ...
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3 votes
1 answer
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A doubt on best media for a time capsule

So, I have some data to a time capsule project of mine. But the thing is, I need to know the best media on long-time scale to use as storage unity. The time range is 120 years. Now, I've been thinking ...
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16 votes
8 answers
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Why we still need Short Term Memory if Long Term Memory can save temporary data?

If RAM is a short term memory and SSD is a long term memory, why don't microarchitecture of computer nowadays use SSD or another long term memory for saving temporary data like hidden variable for ...
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1 answer
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Why did the concept of "write-protecting" not carry over from floppy disks to USB memsticks and especially external USB HDDs? [closed]

Many times, I've wished to plug in my backup hard disks into my PC without the risk of any of the data being deleted, overwritten, or modified in any manner. Purely for "inspection" and ...
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2 answers
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Is ROM primary memory or secondary memory?

According to this picture ROM is classified under Main Memory , but isn’t ROM a secondary storage because it’s external and non volatile ? Any clarification with reference links will be highly ...
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1 answer
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Fair assignment of storage for multiple writers (load balance)

I'm trying to optimize a system with a better algorithm for allocating storage. The system has 'N' writer processes and 'M' disks. (N < 30, M < 10. N can change, M is constant). Any process can ...
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Does writing more data to disk consume more energy than writing less?

As the title says, I am wondering if writing more data (i.e. larger files) to disk (e.g. Tablet SSDs) will consume more energy than smaller files. My expected answer is "yes, because larger files ...
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Course teaching time complexities in real life systems

Having mis-read What course in CS deals with the study of RAM, CPU, Storage? I now wonder what course in CS deals with time and space complexities including GPUs, CPU caches in multiple levels, seek ...
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What course in CS deals with the study of RAM, CPU, Storage?

I watched the Crash Course playlist of Computer Science. It was teaching about RAM, CPU, Storage etc but I felt it was way too fast and only people who have studied the course first hand understood it ...
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Does Nand Flash Type Affect the Read Latency Based on Page Content?

In general, we have these types of NAND flash cells: SLC, MLC, TLC, and QLC. Since MLC flash cells can store 2 bits, the content of the cell can be 00, 01, 10, or 11 which are detected using different ...
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2 answers
5k views

Difference between Sequential ,Direct and Random acess with their acess time

I'm stuck on a point while reading about these different accessing methods. As per author. Sequential access Memory is organized into units of data, called records.Access must be made in a ...
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Why do we need volume as an abstraction on top of partition?

I'm curious about what do we need volume as an abstraction on top of hardware partition? What problem it tries to solve? What is the limitation of this concept?
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Regarding Amdahl's balanced system law

One of the paper titled "Rules of Thumb in Data Engineering" (Jim Gray et. el.) mentions some calculations based on Amdahl's balanced system law. Link to paper: https://www.microsoft.com/en-us/...
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1 answer
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Why does RAID-5 require an additional disk for parity blocks?

I know that RAID-5 consists of block-level striping across multiple disks, but using an additional parity-check block on each disk .. and that at least two disks are required for striping. And it's ...
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2 votes
1 answer
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Page cache and its relationship to page table

I was reading about the page cache Page cache - the cache in memory for files, but I couldn't find the answer to my question. Does the page table have anything to do with, or maintain any entries, for ...
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What exactly is a "binary file"?

I suspect this may be more of a concept / theory question, but, I haven't been able to wrap my brain around what exactly a binary file is. I've read links such as the below: https://en.wikipedia.org/...
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1 vote
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How extended logical blocks are mapped to physical device pages?

I'm reading "Decibel: Isolation and Sharing in Disaggregated Rack-Scale Storage" (PDF). On page 6, the author illustrates the concept of "Extended Logical Block"), which is similar to "Data Integrity ...
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5 votes
1 answer
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Could a standardized ternary system be more efficient than the binary system? [duplicate]

Could a standardized ternary (base-3) system be more efficient than the binary (base-2) system? Binary is efficient for processing using logic gates, but can be bulky when using for file storage or ...
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2 votes
0 answers
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Can you read a file as a binary number?

This is a pretty naive question, but I would like to better understand the basics of information storage on a computer. I am not concerned with the detail of how any one operating system achieves ...
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3 votes
0 answers
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What data structure should I use for storing my data?

I am currently looking for a way in which I can store my data, and quickly look it up. What currently seem to be the best idea is to use a hash map. reasons: To identify what item I am looking for, ...
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How are files managed in a filesystem?

I have recently been interested in low level computer science (as a hobby), and I have just learned about the way a computer organizes and stores information on a hard drive. I have learned the basics ...
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1 answer
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Creating a numbered list, divided into types, without need for shifting or re-ordering - is this a re-occuring problem

My question is not for a solution to the problem, though I do need to put thought into it but rather my question is if this conceptual problem has a name or has been addressed at already in computer ...
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1 vote
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How to calculate multibit trie storage size?

I wish to use a multi-bit trie structure for storing IPv4 forwarding information with a fixed stride width of 8 bits, I think this is also called a "radix of 8" (so for any IP prefix 4 levels will ...
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How is the data stored in AVL tree in a memory? [duplicate]

I have been struggling to visualize how is the AVL tree is stored in memory? Does it store data in array or list, If so how is it connected with its child and parents.
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Comparing the Speed of Random Number Generation to Reading Data

Imagine you need $n$ random numbers from a Gaussian distribution with $\mu=0$ and $\sigma=1$. And you need to use each of these $n$ numbers $k$ times in various operations. Let's identify the numbers ...
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Should we consider number of surfaces in a disk while calculating effective data transfer rate?

Suppose a disk has Number of surfaces: 8 Number of sectors per track: 20 Sector size: 4000B Number of tracks: 10 It is rotating at 360 rpm. So disk is reading data from one track at an instance....
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2 answers
256 views

how does a harddisk work? block / sector [closed]

Can someone explain me the way harddisks work? :/ The size of a block is specified in the filesystem, am I right? As you can see in the picture from wikipedia, the disk is divided into circle sectors. ...
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3 votes
4 answers
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time efficient key value store for fast lookup

Let's state a collection of key/values. Key is an unsigned integer (0 - 2^32-1). Hense there are comparable. Value is few bytes fixed size. There are 4M items in the collection. Keys are not evenly ...
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7 votes
3 answers
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What is the minimum required storage for a sparse, depth-first octree?

For a numerical simulation framework, I use a hierarchical Cartesian grid in 3D to discretize the computational domain. I am thus looking for the most space-efficient way to store the resulting octree ...
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2 answers
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1 bit register with data flip flop doesn't store bit?

A 1-bit register: Credit: Elements of Computing Systems by Noam Nisan and Shimon Schocken ISBN-13: 978-0262640688 I know that the data flip flop outputs the input at the previous time step. ...
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41 votes
9 answers
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Understanding serialization

I am a software engineer and after a discussion with some colleagues, I realized I do not have a good grasp of the concept serialization. As I understand, serialization is the process of converting ...
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Most Efficient Way to List All $n$-bit Permutations

Suppose we are tasked with expressing a randomized list of all numbers up to but excluding $2^n$ (ie. a random list of all n-bit numbers). What are some efficient ways to do such a listing using as ...
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Maximum number of disks in RAID with parity?

From what I understand, to implement RAID 5, one would need a minimum of 3 disks, where 2 would be for data storage, and the third would be for the parity. But what is the maximum number of disks one ...
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-1 votes
1 answer
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Latency vs IOPS. How can one conflict with the other?

I was reading about latency and IOPS, and I understood what they mean and their significance in the storage world. But what I do not understand (many places it is mentioned) is that how can the ...
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How storage affect if we use tertiary language? [duplicate]

as we uses binary language in all the computer systems around us which consist of 0s and 1s (Off and On) bits. Let assume that someone is developing a computer system based on tertiary system -1, 0, 1 ...
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1 vote
1 answer
545 views

How are the number of bytes less than the number of pixels in an image?

Lets take, for example this jpeg image here The image there is 400 x 300, or 120000 pixels and The file size of the image (on my computer) is shown to be 65171 bytes. This means the computer stores ...
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3 votes
1 answer
135 views

Is there a name for "density" of information?

If we compare multimedia and text, if we have n bytes of text and compare it with n bytes of video, then we would be likely to think that n bytes of text is "more" information than n bytes of video ...
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3 votes
0 answers
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Representing Computations on Transcendental Numbers

Consider the set of transcendental numbers that are not compressible to a finite base-2 representation. How can I compute multiples (more generally, any algebraic computation) of one of these numbers,...
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-3 votes
1 answer
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Determining HD Content [closed]

A storage system has 6 hard drives set up as RAID 5, where HD 6 is the parity disk using odd parity. One day, the system crashes due to failure of HD4. During recovery, we find out that HD1 stores ...
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1 vote
1 answer
188 views

How can I formalize key value stores with set theory?

I'm currently developing a simple key-value NoSQL store and want to build its formal model. I found article about key value formalisation with category theory, but I'm interested are there some works ...
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0 votes
1 answer
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Why do computers use binary, instead of ternary, or some other logic system? [duplicate]

In binary a unit (bit), can store 2 separate values. if you have ternary, then a unit can store 3 separate values. why then don't computers use higher bases, for example in ternary you could have 3 ...
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1 vote
2 answers
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Why don't hard drives actually delete data?

As far as I understand it, when you delete a file from trash/recycle bin the file isn't actually erased from memory but is instead marked as being okay to be over written. So, my question is as to ...
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5 votes
4 answers
445 views

A "triangular" data structure for commutative relationships

A multiplication table is symmetric over a diagonal, so only about $n^2/2$ of the elements in an $n \times n$ multiplication table contain unique information. Same goes for addition tables. In fact, ...
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1 answer
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How to store factorials? [closed]

Can someone help me to store the factorial of large numbers such as 100! efficiently? UPDATE: obviously, storing the argument rather than the factorial digits themselves achieves a significant saving....
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4 votes
0 answers
63 views

Extending the causal memory model to wide-area distributed storage systems

In the seminal paper "Causal memory: definitions, implementations, and programming", distributed causal memory is defined to ensures that all the processes in a system agree on the relative ordering ...
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1 vote
1 answer
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Why is data stored on a flash disk irretrievable if the memory chip is cracked? [closed]

All data recovery companies, regardless of skill, unanimously say that if the memory chip of a device has just a hair line crack, data recovery is impossible. Not unlikely, not expensive, but ...
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